Newsletter - January 2005

Note: The following summaries are based on articles from the press and from peer-reviewed publications, and they represent the opinions of the original authors. The views of authors expressed herein do not necessarily state or reflect those of the United States Government, and shall not be used for advertising or product endorsement purposes. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government.

Journal Articles

Excess mercury levels increasing: Survey shows one-fifth of women of childbearing age are affected. One-fifth of women of childbearing age have mercury levels in their hair that exceed federal health standards, according to interim results of a nationwide survey commissioned by Greenpeace and being conducted by researchers at the University of North Carolina at Asheville (UNCA). Researchers at UNCA based their findings on hair samples from nearly 1,500 people, many of whom learned of the study through the Internet. Participants either paid $25 to submit hair samples with a home testing kit or received free tests at 27 hair salons across the country. The author of the report, Richard Maas, said the tests showed a correlation between how much fish people ate and their mercury levels; for example, one-third of people who ate canned tuna four or more times a week had mercury levels above U.S. Environmental Protection Agency (EPA) recommendations. The last major national study of Americans' mercury exposure, conducted by the Centers for Disease Control and Prevention in 1999 and 2000, concluded that about 12 percent of women of childbearing age had mercury levels that exceeded EPA's safety standard. The new study found excess mercury levels in 21 percent of the 597 women of childbearing age who were tested. UNCA researchers said they could not explain why these subjects had higher mercury levels, and 80 percent of study participants said they had no reason to think they had high concentrations of mercury in their blood. Men and women in the study had similar mercury levels. EPA spokeswoman Cynthia Bergman said "We are addressing this shared concern on all fronts - making sure consumers, particularly pregnant women or women who may become pregnant, have clear guidance about the benefits and risks of fish consumption - as well as attacking the problem at its source by regulating mercury emissions from power plants for the very first time. Mercury is a serious health risk."

Eilperin, Juliet. 2004. The Washington Post. October 21, Page A02.

Flame retardant PBDEs found in Lake Michigan, adding to concerns. Concentrations of flame retardant polybrominated diphenyl ethers (PDBEs), banned by many European countries, have been found and are increasing in Lake Michigan, adding to concerns over previous findings that the chemicals were showing up in supermarket foods and women's breast milk. In the latest study, sponsored by the National Oceanic and Atmospheric Administration, University of Wisconsin scientists found PBDEs in sediment located hundreds of feet down in Lake Michigan. The three-year study found PBDEs of up to one part per billion (ppb) in the lake sediment. By dating the samples of PBDEs, scientists also found that the concentrations were increasing. In 2001, scientists Sonzogni and Manchester also found that Lake Michigan's top predator fish - coho and Chinook salmon - had PBDEs at concentrations exceeding 100 ppb, among the highest measured in open-water fish anywhere in the world. No direct correlation has been shown between PBDEs and specific diseases or developmental impairment, and the government has not set any level of use that is considered safe in food.

The Associated Press. 2004. November 24.

Canada reviewing fish consumption guidelines because of mercury fears. Mounting evidence that mercury contamination can damage fetal brain development has pushed Health Canada to review its guidelines on fish consumption by women of childbearing age, The Canadian Press has learned. The review comes amid mounting international concern about mercury, with U.S. authorities adopting guidelines for fish consumption that are far stricter than their Canadian counterparts. Health Canada has no general warning on seafood consumption, although it recommends that women limit consumption of several high-mercury species, including shark, swordfish, and fresh or frozen tuna. "We are currently in the process of collecting and reviewing data on mercury levels in different fish species, and that review might result in some changes to the guidance," Health Canada expert John Salminen said in an interview. The U.S. Environmental Protection Agency now says that mercury levels in maternal blood should not exceed 5.8 ppb, which is more than three times lower than Health Canada's limit of 20 ppb.

Canada's aboriginal people, the Inuit, have high blood-mercury levels, mainly because of their high fish consumption, although hydroelectric development may also be a factor (mercury naturally present in rocks is released in a more dangerous form by microbial processes when vegetation is flooded). Child-development expert Gina Muckle of Laval University examined 110 Inuit babies from 1996 to 2001 and found evidence of subtle neurological damage that was correlated to high levels of mercury in the blood. The study involved placing a baby's toy in one of two containers, and then distracting the child for a few seconds. The babies with higher blood mercury levels more readily forgot the hiding place.

Jay van Oostdam, adviser in Health Canada's Environmental Contaminants Bureau, says the department has to be careful in communicating the risk of mercury for fear of driving people away from nutritious fish. Protecting the traditional lifestyle of aboriginals is a major concern, he adds. "We've got to be careful that we address the important health issues up there and we don't scare them off traditional foods and they have to buy expensive southern foods, which are not as nutritious as their traditional foods."

Bueckert, Dennis. 2004. The Canadian Press. November 20.

Groups say Houston area fish samples have mercury. Local environmental groups in Houston, Texas, believe people should be concerned about the fish they eat after lab tests showed that randomly collected fish samples from the area had unsafe levels of mercury. The Galveston-Houston Association for Smog Prevention, along with Mothers for Clean Air and the Texas Public Interest Research Group, released a report that included data from area fish samples, as well as data from recent U.S. Environmental Protection Agency studies. Although three of the four samples of fish either bought in stores or caught in local waters by the groups had unsafe mercury levels, the report did find that fish from Galveston Bay and farmed fish were safe.

The Associated Press. 2004. October 15.

Tests find Alaska fish contaminant levels low. Alaska's world-famous seafood continues to live up to claims that it is hauled from some of the cleanest waters in the United States. Test results from state and private fish monitoring programs find that Alaska seafood is free from contamination levels that would raise public health concerns. So far, these studies show contamination levels far below those deemed dangerous to humans by the Centers for Disease Control, the U.S. Environmental Protection Agency (EPA), and the World Health Organization, according to the Alaska Division of Environmental Health. Using funding from the EPA and the National Oceanic and Atmospheric Administration, division researchers are analyzing samples of all five species of Alaska salmon, as well as halibut, Pacific cod, sablefish, black rockfish, sheefish, lingcod, and pollock. Researchers are looking for traces of heavy metals, such as methyl mercury, lead and cadmium, as well as conducting other tests to detect dioxins and furans, pesticides, polychlorinated biphenyl (PCB) congeners, inorganic arsenic, and chromium VI. Samples are being collected primarily in marine waters throughout Alaska, with some northern pike collected from lakes in the Koyukuk, Kuskokwim, Yukon, and Susitna River drainages.

The Associated Press. 2004. October 10.

Canadian scientists say tuna contains mercury and should be labeled. Scientists say fish should be labeled to make consumers aware of how much mercury they may be consuming. Health Canada warns against eating too much fresh tuna, shark, and swordfish, but studies by a Montreal environmental health expert suggests some kinds of canned tuna also contain significant amounts of mercury.

At a meeting of Canada's Collaborative Mercury Research Network, one representative recommended a fish labeling system that uses a color scheme that would indicate mercury concentration. For example, pale (light) tuna could be labeled with a green dot, and white tuna, which has 10 times the mercury, could be labeled with a red dot. A red dot on albacore tuna would indicate consumers should only eat the fish once a month, and that pregnant women should avoid the fish completely. A similar color-coded system was developed for people in the Amazon, where fish is eaten on daily basis.

Manitoba Conservation publishes and distributes a guide for fisherman on how often fish of different sizes can be safely consumed by anglers.

The Associated Press. 2004. November 5.

Selenium and other trace elements in water, sediment, aquatic plants, aquatic invertebrates, and fish from streams in southeast Idaho near phosphate mining. In June 2000, nine stream sites in the Blackfoot River watershed in southeast Idaho were sampled for water, surficial sediment, aquatic plants, aquatic invertebrates, and fish. The stream sites include the Angus Creek, upper and lower East Mill Creek, Trail Creek, upper and lower Slug Creek, Sheep Creek, Dry Valley Creek, and lower Blackfoot River. Researchers measured selenium and other elements in the aquatic ecosystem components and performed a hazard assessment. Water quality parameters were relatively uniform among the nine sites examined. Of the aquatic components evaluated, water provided the least information, especially its analysis for selenium contamination, because measured levels were well below the national water quality criterion of 5 parts per billion (ppb). Selenium and several other elements, however, were elevated in sediment, aquatic plants, and aquatic invertebrates from a number of sites and indicated accumulation in sediments and cycling through plants and invertebrates. Only selenium in fish was elevated to concentrations of potential concern. A selenium hazard assessment suggested a low hazard at Trail Creek and Sheep Creek, a moderate hazard at upper and lower Slug Creek, and a high hazard at Angus Creek near the mouth, upper, and lower East Mill Creek, Dry Valley Creek, and lower Blackfoot River.

Blood mercury levels in young children and childbearing-aged women-United States, 1999-2002. Exposure to high concentrations of mercury can cause neurological and renal disorders. Because methylmercury in aquatic systems accumulates in animal tissues up the food chain, fish consumers in the United States can be exposed to mercury by eating freshwater fish, seafood, and shellfish. Exposure of childbearing-aged women is of particular concern because of the potential adverse neurological effects of mercury to fetuses. To assess total blood mercury concentrations in childbearing-aged women and in children aged 1 to 5 years in the United States, the Center for Disease Control's National Health and Nutrition Examination Survey (NHANES) measured blood mercury levels in these groups in 1999. This report summarizes NHANES results for the period 1999-2002 and updates previously published information. Findings confirmed that blood mercury levels in young children and women of childbearing age usually are below levels of concern; however, approximately 6 percent of childbearing-aged women had blood concentrations at or above a reference dose, an estimated level assumed to be without appreciable harm (> or =5.8 parts per billion [ppb]). Women who are pregnant or who intend to become pregnant should follow federal and state advisories on consumption of fish and shellfish.

Morbidity Mortality Weekly Report. 2004. 53 (43): 1018-20.

The public health implications of PCBs in the environment. Polychlorinated biphenyls (PCBs) were widely used in a variety of industrial applications before their commercial production was banned in 1979. Some PCB congeners have been shown to degrade slowly in the environment and can build up in the food chain. Several health agencies have classified PCBs as animal carcinogens; however, epidemiological studies of workers exposed to high doses of PCBs have not demonstrated increased cancer risk. PCB-related health effects include skin and eye irritation. No reliable evidence exists that PCBs in the environment result in either endocrine disruption or intellectual deterioration in children exposed in utero. The author believes that because PCB exposures from environmental sources do not pose a significant health risk, little benefit to public health can result from continued remediation of PCB sources.

Ross, G. 2004. Ecotoxicology and Environmental Safety 59 (3): 275-91.

Hair mercury levels versus freshwater fish consumption in household members of Swedish angling societies. Hair mercury levels were analyzed from 143 individuals from households of members of fishing societies in an area of Sweden containing many lakes that have mercury-contaminated freshwater fish. The study group, therefore, had a potentially high intake of methyl mercury via their consumption of mercury-contaminated fish. Mean mercury levels of pike and perch were 0.7 parts per million (ppm), and one-third of the study group ate freshwater fish at least once a week. As expected, there was an increase in hair mercury levels with reported freshwater fish consumption (P < 0.001). The median mercury hair level was 0.9 ppm for the study group as a whole, and 1.8 ppm for those who reported consumption of fish at least once a week. The highest hair mercury concentration was 18.5 ppm, detected in a man who consumed pike and perch several times per week. Overall, the authors found that men had higher hair mercury than women, when stratified for fish consumption. This was verified in 32 couples, where the man and woman consumed the same fish and reported the same consumption. Median hair mercury levels in these 32 couples averaged 1.3 ppm for men and 0.8 ppm for women. Half of the subjects had hair mercury levels greater than 1 ppm, which corresponds to the reference dose (RfD) of 0.1 microgram of mercury per kilogram body weight set by the U.S. Environmental Protection Agency. Although the RfD applies to all populations, the most at-risk group at these levels is pregnant women. Only 2 women (out of 12) of fertile age had hair mercury levels greater than 1 ppm. In Sweden, pregnant women are advised not to eat perch and pike at all during pregnancy.

Mercury in canned tuna: white versus light and temporal variation. Abundant data for mercury levels in wild fish and resulting fish advisories exist, but much less data are available for the commercial fish that most people eat, such as canned tuna. Despite its importance in human diets, relatively little attention has been devoted to examining mercury concentrations in canned tuna. Canned tuna is the most commonly consumed fish in the United States. This study examines the total mercury concentrations in canned tuna obtained from a New Jersey grocery store from 1998 to 2003. The authors looked for temporal consistency within this data set and for comparison with the U.S. Food and Drug Administrations (FDA's) 1991 study. The authors analyzed 168 cans individually for total mercury (parts per million [ppm] wet weight basis), and a subset of samples was analyzed for total and inorganic mercury. The inorganic mercury was below detection levels; therefore, at least 89 percent of the mercury was considered to be methylmercury. White meat tuna contained significantly more total mercury (mean 0.407 ppm) than light tuna (mean 0.118 ppm). This likely reflects the fact that white tuna is albacore, a species relatively larger than the skipjack tuna, commonly available as light. The maximum mercury level detected was 0.997 ppm, but 25 percent of white tuna samples exceeded 0.5 ppm. Data suggest a slight increase in concentrations since 1991, and mercury levels were significantly higher in 2001 than in other years. The mean mercury concentration in white tuna (mean 0.407 ppm) was significantly higher than the 0.17 ppm level currently used by the FDA in its risk assessment. Study results indicate that people who eat canned tuna frequently can choose to eat light tuna and thereby reduce their mercury intake.

Intestinal absorption and biomagnification of organic contaminants in fish, wildlife, and humans. The authors provide a review of the current state of knowledge regarding mechanisms and models of intestinal absorption and biomagnification of organic chemicals in organisms of aquatic and terrestrial food chains. The review also provides a discussion of the implications of these models for assessing the bioaccumulation potential of organic chemicals. Four mechanistic models, including (1) biomass conversion, (2) digestion or gastrointestinal magnification, (3) micelle-mediated diffusion, and (4) fat-flush diffusion, are compared. The models represent an evolution in understanding of chemical bioaccumulation processes and have some similarities. An important difference between the biomagnification models is whether intestinal absorption of an ingested contaminant occurs solely via passive molecular diffusion through serial resistances or via facilitated diffusion that incorporates an additional transport mechanism. This difference has an effect on the selection of physicochemical properties that best anticipate the bioaccumulative potential of commercial chemicals in aquatic and terrestrial food chains. The authors urge that further research be conducted on dietary absorption and biomagnification of organic chemicals to develop better bioaccumulative models for organic chemicals.

American Fisheries Society 135th Annual Meeting. The 135th Annual Meeting of the AFS will be held at the Egan Convention Center and Performing Arts Center in Anchorage, Alaska September 11-15, 2005. The meeting's theme will be "Creating A Fisheries Mosaic: Connections Across Jurisdictions, Disciplines, and Cultures." Get more information and register here: http://www.wdafs.org/Anchorage2005/index.htm